1. Field of the Invention
The present invention relates to a wiring thin plate applied to a flexure of a head suspension or the like, the flexure of the head suspension and a method of welding the wiring thin plate.
2. Description of Related Art
A hard disk drive incorporates hard disks that are provided so as to rotate at high speed and head suspensions with sliders that are slightly lifted from the respective hard disks to write/read data to and from the hard disks. FIG. 28 illustrates a head suspension with a slider disclosed in JP2008-71401A. The head suspension 100 includes a load beam 101, a base plate 103 and a flexure 105 attached to the load beam 101 and the base plate 103.
The flexure 105 includes a wiring part 109 provided on a metal substrate 107 and a tongue 110 on which a slider 111 is supported. The slider 111 includes read/write elements to which the wiring part 109 is connected. In the head suspension, the flexure 105 is joined to the load beam 101 and the base plate 103 at welded spots 113, 115, 117, 119 and the like by laser welding in general. A tail portion 105a of the flexure 105 extends outward from the base plate 103.
The welded spots 113, 115, 117 and 119 are provided at appropriate locations between wiring traces and/or out of the wiring traces or the like in view of locational balance among the welded spots and of locational spaces. In the case of the welded spots 117 and 119 provided between the wiring traces, a location between paired wiring traces is avoided for the locations of the welded spots 117 and 119 to prevent deterioration in electric characteristic.
When conducting the laser welding to join the flexure 105 having the wiring to the load beam 101 and the base plate 103, it is extremely important for quality of the welded spots that the flexure 105 is brought into close contact with the load beam 101 and the base plate 103. If the close contact is insufficient to involve a gap, the laser welding may form a hole and cause scattering and deformation on the flexure 105, the load beam 101 and the base plate 103 to form a defective nugget.
A metal substrate 107 of the flexure 105 is so thin that a portion around a location to be welded needs to be firmly held down by a welding jig.
FIG. 29 is a schematic plan view partly illustrating the head suspension around one welded spot of FIG. 28, FIG. 30 is a schematic sectional view partly illustrating the same as well as a welding jig. FIG. 31 is a plan view partly illustrating a small head suspension to which a flexure is attached, FIG. 32 is a schematic plan view partly illustrating a welded spot of the head suspension of FIG. 31 and FIG. 33 is a schematic sectional view partly illustrating the same as well as a welding jig.
As illustrated in FIGS. 28 to 30, the conventional head suspension has a sufficient space to form relatively-large projections 114 that outwardly protrude from the wiring part 109. When the welded spots 113 are formed on the projections 114, each projection 114 is easily held down around the welded spot 113 with a circumferential holding portion 123b of a welding jig 123 through which a through hole 123a goes.
A recent head suspension, however, is downsized according to downsizing of a hard disk and also involves widened wiring traces. As illustrated in FIG. 31, therefore, the projections 125 outwardly protruding from the wiring part 109 in the downsized head suspension have to be downsized. This makes it hard to hold down each projection 125 around the welded spot 129 with the conventional welding jig 127.
To solve the problem, the holding portion 127b of the welding jig 127 may be downsized as illustrated in FIGS. 32 and 33, The downsized holding portion 127b, however, does not effectively hold down the projection 125 if the welding jig 127 is deviated or shifted even a little from the most appropriate position.
In particular, the laser welding in practice is conducted to a plurality of semi-finished products that are chained together with a frame to produce a plurality of head suspensions. For this, the welding jig 127 has a plurality of united holding portions 127b for the respective chained semi-finished products. The united holding portions 127b of the welding jig 127 are positioned to the chained semi-finished products, respectively. Thus, each one holding portion 127b is likely to deviate from the corresponding projection 125 or location to be welded, to cause a problem of the ineffective holding.
Such a problem is occurred at not only the projection 125 formed to the flexure 105 and welded to the load beam 101 but also a projection welded to the base plate and a location between the wiring traces other than the projection. Further, such the problem may be occurred in a wiring thin plate for other products.